Counting single chromophore molecules for ultrasensitive analysis and separations on microchip devices

Area of Science:

• Analytical Chemistry
• Microfluidics
• Spectroscopy

Background:

• Microchip electrophoresis offers miniaturized and efficient chemical separations.
• Sensitive detection methods are crucial for analyzing low-concentration analytes in microdevices.
• Traditional detection methods can be limited in sensitivity and throughput.

Purpose of the Study:

• To develop and validate a single-molecule counting technique for microchip electrophoresis.
• To achieve ultra-low concentration detection limits for fluorescent analytes.
• To demonstrate the capability of this method for rapid chemical separations.

Main Methods:

• Utilizing a micromachined electrophoresis channel for sample separation.
• Detecting analytes by counting individual fluorescence bursts from single molecules.
• Estimating migration times, peak widths, and concentrations from molecular counts and distributions.

Main Results:

• Achieved concentration detection limits of 1.7 pM for rhodamine 6G and 8.5 pM for rhodamine B.
• Separations were completed in under 35 seconds with migration time uncertainties below 2.0%.
• Demonstrated the first application of single-chromophore molecular counting for chemical separation detection.

Conclusions:

• Single-molecule counting provides ultra-sensitive detection in microchip electrophoresis.
• This method sets new benchmarks for detection limits in microseparation devices.
• The technique is promising for high-sensitivity, rapid chemical analysis in miniaturized systems.